Pleistocene Megafauna Extinctions Were Caused by BOTH Humans AND Climate Change?

Giant Ice Age species including elephant-sized sloths and powerful sabre-toothed cats that once roamed the windswept plains of Patagonia, southern South America, were finally felled by a perfect storm of a rapidly warming climate and humans, a new study has shown.

Research led by the Australian Centre for Ancient DNA (ACAD) at the University of Adelaide, published today in Science Advances, has revealed that it was only when the climate warmed, long after humans first arrived in Patagonia, did the megafauna suddenly die off around 12,300 years ago.

The timing and cause of rapid extinctions of the megafauna has remained a mystery for centuries.

"Patagonia turns out to be the Rosetta Stone - it shows that human colonisation didn't immediately result in extinctions, but only as long as it stayed cold," says study leader Professor Alan Cooper, ACAD Director. "Instead, more than 1000 years of human occupation passed before a rapid warming event occurred, and then the megafauna were extinct within a hundred years."

link.

The Tools and Weapons Used to Hunt Mammoths in Poland 24,000 Years ago

Mammoth hunting – Impact traces on backed implements from a mammoth bone accumulation at Kraków Spadzista (southern Poland)
Authors:

Kufel-Diakowska et al

Abstract:

This article presents the results of use-wear analysis of the backed implements (shouldered points and backed blades) discovered at Kraków Spadzista, trench B + B1. Of the 197 examined tools, 113 specimens (55%) bear traces of use. In this group, 55 artefacts show a complete set of clear, characteristic impact traces and could be interpreted as the flint parts of thrown weapons. They were used in mammoth hunting at the Kraków Spadzista site 24 thousand years ago. The hafting method can be identified on the basis of the direction of linear traces and impact negatives. Most of these artefacts were placed at the top of wooden or bone shaft. Only single specimens were attached laterally.

Give Thanks! That Pumpkin Pie You're Eating Only Exists Because the Mastodons, Other Pleistocene Megafauna Went Extinct

If Pleistocene megafauna -- mastodons, mammoths, giant sloths and others -- had not become extinct, humans might not be eating pumpkin pie and squash for the holidays, according to an international team of anthropologists.

"It's been suggested before and I think it's a very reasonable hypothesis, that wild species of pumpkin and squash weren't used for food early in the domestication process," said Logan Kistler, NERC Independent Research Fellow, University of Warwick, U.K. and recent Penn State postdoctoral fellow. "Rather, they might have been useful for a variety of other purposes like the bottle gourd, as containers, tools, fishnet floats, etc. At some point, as a symbiotic relationship developed, palatability evolved, but the details of that process aren't known at the present."

Researchers believe that initially humans did not eat wild pumpkin and squash -- members of the cucurbita family -- because the wild fruit is not only bitter but also toxic to humans and smaller animals. However, clear evidence exists that very large animals -- megafauna -- that lived 12,000 years ago did eat these fruit.

"Lee Newsom (associate professor of anthropology, Penn State and study co-author) has recovered many wild gourd/squash seeds from ancient Mastodon dung, suggesting that large herbivores may have been an important feature in the natural history of these wild plants," said Kistler.

The researchers looked at varieties of modern domestic cucurbits, modern wild cucurbits and archaeological specimens. They believe that changes in distribution of the wild plants are directly related to the disappearance of the large animals.

link.

Pleistocene Quaternary Giant Mammals Became Extra Vulernable to Extinction due to Habitat Fragmentation?

Life and extinction of megafauna in the ice-age Arctic

Authors:

Mann et al

Abstract:

Understanding the population dynamics of megafauna that inhabited the mammoth steppe provides insights into the causes of extinctions during both the terminal Pleistocene and today. Our study area is Alaska's North Slope, a place where humans were rare when these extinctions occurred. After developing a statistical approach to remove the age artifacts caused by radiocarbon calibration from a large series of dated megafaunal bones, we compare the temporal patterns of bone abundance with climate records. Megafaunal abundance tracked ice age climate, peaking during transitions from cold to warm periods. These results suggest that a defining characteristic of the mammoth steppe was its temporal instability and imply that regional extinctions followed by population reestablishment from distant refugia were characteristic features of ice-age biogeography at high latitudes. It follows that long-distance dispersal was crucial for the long-term persistence of megafaunal species living in the Arctic. Such dispersal was only possible when their rapidly shifting range lands were geographically interconnected. The end of the last ice age was fatally unique because the geographic ranges of arctic megafauna became permanently fragmented after stable, interglacial climate engendered the spread of peatlands at the same time that rising sea level severed former dispersal routes.

Extinction of Pleistocene Megafauna Allowed Forests to Expand

Combining paleo-data and modern exclosure experiments to assess the impact of megafauna extinctions on woody vegetation

Authors:

Bakker et al

Abstract:

Until recently in Earth history, very large herbivores (mammoths, ground sloths, diprotodons, and many others) occurred in most of the World’s terrestrial ecosystems, but the majority have gone extinct as part of the late-Quaternary extinctions. How has this large-scale removal of large herbivores affected landscape structure and ecosystem functioning? In this review, we combine paleo-data with information from modern exclosure experiments to assess the impact of large herbivores (and their disappearance) on woody species, landscape structure, and ecosystem functions. In modern landscapes characterized by intense herbivory, woody plants can persist by defending themselves or by association with defended species, can persist by growing in places that are physically inaccessible to herbivores, or can persist where high predator activity limits foraging by herbivores. At the landscape scale, different herbivore densities and assemblages may result in dynamic gradients in woody cover. The late-Quaternary extinctions were natural experiments in large-herbivore removal; the paleoecological record shows evidence of widespread changes in community composition and ecosystem structure and function, consistent with modern exclosure experiments. We propose a conceptual framework that describes the impact of large herbivores on woody plant abundance mediated by herbivore diversity and density, predicting that herbivore suppression of woody plants is strongest where herbivore diversity is high. We conclude that the decline of large herbivores induces major alterations in landscape structure and ecosystem functions.

pop sci write up. 2nd one.

Large Pleistocene Carnivores had a Huge Impact on the Ecology

The impact of large terrestrial carnivores on Pleistocene ecosystems

Authors:

Van Valkenburgh et al

Abstract:

Large mammalian terrestrial herbivores, such as elephants, have dramatic effects on the ecosystems they inhabit and at high population densities their environmental impacts can be devastating. Pleistocene terrestrial ecosystems included a much greater diversity of megaherbivores (e.g., mammoths, mastodons, giant ground sloths) and thus a greater potential for widespread habitat degradation if population sizes were not limited. Nevertheless, based on modern observations, it is generally believed that populations of megaherbivores (>800 kg) are largely immune to the effects of predation and this perception has been extended into the Pleistocene. However, as shown here, the species richness of big carnivores was greater in the Pleistocene and many of them were significantly larger than their modern counterparts. Fossil evidence suggests that interspecific competition among carnivores was relatively intense and reveals that some individuals specialized in consuming megaherbivores. To estimate the potential impact of Pleistocene large carnivores, we use both historic and modern data on predator–prey body mass relationships to predict size ranges of their typical and maximum prey when hunting as individuals and in groups. These prey size ranges are then compared with estimates of juvenile and subadult proboscidean body sizes derived from extant elephant growth data. Young proboscideans at their most vulnerable age fall within the predicted prey size ranges of many of the Pleistocene carnivores. Predation on juveniles can have a greater impact on megaherbivores because of their long interbirth intervals, and consequently, we argue that Pleistocene carnivores had the capacity to, and likely did, limit megaherbivore population sizes.

Nearly Wiping out Sea Otters Helped Drive Stellar Sea Cows to Extinction

Sea otters, kelp forests, and the extinction of Steller’s sea cow

Authors:

Estes et al

Abstract:

The late Pleistocene extinction of so many large-bodied vertebrates has been variously attributed to two general causes: rapid climate change and the effects of humans as they spread from the Old World to previously uninhabited continents and islands. Many large-bodied vertebrates, especially large apex predators, maintain their associated ecosystems through top-down forcing processes, especially trophic cascades, and megaherbivores also exert an array of strong indirect effects on their communities. Thus, a third possibility for at least some of the Pleistocene extinctions is that they occurred through habitat changes resulting from the loss of these other keystone species. Here we explore the plausibility of this mechanism, using information on sea otters, kelp forests, and the recent extinction of Steller's sea cows from the Commander Islands. Large numbers of sea cows occurred in the Commander Islands at the time of their discovery by Europeans in 1741. Although extinction of these last remaining sea cows during early years of the Pacific maritime fur trade is widely thought to be a consequence of direct human overkill, we show that it is also a probable consequence of the loss of sea otters and the co-occurring loss of kelp, even if not a single sea cow had been killed directly by humans. This example supports the hypothesis that the directly caused extinctions of a few large vertebrates in the late Pleistocene may have resulted in the coextinction of numerous other species.

Radiocarbon Dating Further Supports Human Overkill Hypothesis

Radiocarbon analysis of the decline and extinction of large mammals in the Americas lends support to the idea that hunting by humans led to the animals' demise -- and backs the generally accepted understanding of when humans arrived in, and how they colonized, the Western Hemisphere.

Those findings by University of Wyoming researchers are reported this week in an article published in the Proceedings of the National Academy of Sciences, a major scientific journal. The study was conducted by Professor Todd Surovell and graduate student Spencer Pelton in UW's Department of Anthropology; Professor Richard Anderson-Sprecher in the Department of Statistics; and Assistant Professor Adam Myers in the Department of Physics and Astronomy.

Their work supports a hypothesis forwarded in 1973 by well-known geoscientist Paul Martin that the chronology of the extinction of animals such as mammoths, mastodons, camels, horses and ground sloths in the Americas could be used to map the spread of humans through the New World.

"The heavy ecological footprint of human societies throughout prehistory is becoming increasingly apparent through a variety of environmental (indicators) independent of the archeological record," the researchers wrote. "Past human societies have disrupted ecological communities in dramatic ways for many tens, if not hundreds of thousands, of years."

The study involved compiling radiocarbon dates from fossils of now-extinct animals from North and South America, and looking at how those dates correspond with initial evidence of human colonization. The researchers found that, as Martin predicted, decline and extinction of the large mammals began between 13,300-15,000 years ago in Alaska and areas near the Bering Strait; between 12,900-13,200 years ago in the contiguous United States; and between 12,600-13,900 years ago in South America.

That supports the generally accepted understanding of how humans colonized the Americas: first, that they crossed from Siberia to Alaska across a Bering Strait land bridge; and then that they moved southward across North America and into South America. Hunting of the native large mammals is thought to have fueled rapid human population growth and expansion.

A number of hypotheses have been forwarded to explain the extinction of those animals. The "overkill hypothesis" connects their demise directly to overhunting by humans, and that is supported by the north-to-south extinction trend observed in the new study.

link.

paper link.

12,000 Year Old Michigan Mammoth Likely Butchered by PaleoIndians

Paleontologists from the University of Michigan have uncovered a thrilling find only 10 miles south of Ann Arbor near the town of Chelsea, Michigan. A partial skeleton of a 12,000 year old mammoth was discovered—including parts of its skull, tusks, pelvis, and shoulder blades—but that’s not all. Dig leader and University of Michigan professor of paleontology Daniel Fisher said that the site has “excellent evidence of human activity” preserved with the mammoth remains.

link.

The Spread and Distrbution of Humanity in Holocene Quaternary North America

Spatiotemporal distribution of Holocene populations in North America

Authors:

Chaput et al

Abstract:

As the Cordilleran and Laurentide Ice Sheets retreated, North America was colonized by human populations; however, the spatial patterns of subsequent population growth are unclear. Temporal frequency distributions of aggregated radiocarbon (14C) dates are used as a proxy of population size and can be used to track this expansion. The Canadian Archaeological Radiocarbon Database contains more than 35,000 14C dates and is used in this study to map the spatiotemporal demographic changes of Holocene populations in North America at a continental scale for the past 13,000 y. We use the kernel method, which converts the spatial distribution of 14C dates into estimates of population density at 500-y intervals. The resulting maps reveal temporally distinct, dynamic patterns associated with paleodemographic trends that correspond well to genetic, archaeological, and ethnohistoric evidence of human occupation. These results have implications for hypothesizing and testing migration routes into and across North America as well as the relative influence of North American populations on the evolution of the North American ecosystem.

Giant Monitor Lizards Survived in Australia at Least Until Humans Arrived

As if life wasn't hard enough during the last Ice Age, research led by the University of Queensland has found Australia's first human inhabitants had to contend with giant killer lizards.

UQ vertebrate palaeoecologist Dr Gilbert Price said researchers working in Central Queensland were amazed when they unearthed the first evidence that Australia's early human inhabitants and giant apex predator lizards had overlapped.

"Our jaws dropped when we found a tiny fossil from a giant lizard during a two metre deep excavation in one of the Capricorn Caves, near Rockhampton," Dr Price said.

"The one-centimetre bone, an osteoderm, came from under the lizard's skin and is the youngest record of a giant lizard on the entire continent."

Dr Price and his colleagues used radiocarbon and uranium thorium techniques to date the bone as about 50,000 years old, coinciding with the arrival of Australia's Aboriginal inhabitants.

"We can't tell if the bone is from a Komodo dragon -- which once roamed Australia -- or an even bigger species like the extinct Megalania monitor lizard, which weighed about 500kg and grew up to six metres long," Dr Price said.

"The find is pretty significant, especially for the timeframe that it dates."

link.

Pleistocene Quaternary Megafaunal Communities Became More Vulnerable After Human Arrival

Pleistocene megafaunal interaction networks became more vulnerable after human arrival

Authors:

Pires et al

Abstract:

The end of the Pleistocene was marked by the extinction of almost all large land mammals worldwide except in Africa. Although the debate on Pleistocene extinctions has focused on the roles of climate change and humans, the impact of perturbations depends on properties of ecological communities, such as species composition and the organization of ecological interactions. Here, we combined palaeoecological and ecological data, food-web models and community stability analysis to investigate if differences between Pleistocene and modern mammalian assemblages help us understand why the megafauna died out in the Americas while persisting in Africa. We show Pleistocene and modern assemblages share similar network topology, but differences in richness and body size distributions made Pleistocene communities significantly more vulnerable to the effects of human arrival. The structural changes promoted by humans in Pleistocene networks would have increased the likelihood of unstable dynamics, which may favour extinction cascades in communities facing extrinsic perturbations. Our findings suggest that the basic aspects of the organization of ecological communities may have played an important role in major extinction events in the past. Knowledge of community-level properties and their consequences to dynamics may be critical to understand past and future extinctions.

Refugia Identified for New Zealand Seabirds From Maori Overhunting

An international research team led by University of Otago scientists has documented prehistoric "sanctuary" regions where New Zealand seabirds survived early human hunting.

The researchers used ancient-DNA analysis, radiocarbon dating and computational modelling to reconstruct population histories for prehistoric seabirds around coastal New Zealand.

Dr Nic Rawlence, who carried out the genetic study, says the team found a very distinctive pattern, where shag/mapua (Leucocarbo chalconotus) populations from the Stewart Island region were little affected by human hunting, but mainland populations were rapidly decimated.

"There was a loss of more than 99% of their population size within 100 years of human arrival. These once heavily-hunted mainland populations now occupy only a fraction of their prehistoric range, having never really recovered," Dr Rawlence says.

The study suggests that the mainland populations survived on just a few rocky islands off the South Island's east coast.

"By comparison, the Stewart Island populations have experienced a relatively stable history," Dr Rawlence says.

Associate Professor Ian Smith, an Otago archaeologist involved in the study, says it seems that these contrasting wildlife histories reflect differences in prehistoric human-hunting pressure.

"Interestingly, recent archaeological studies suggest that human numbers declined in the Stewart Island region around 1500 AD, a factor which seems to explain why wildlife persisted in this region," he says.

link.

Academic Bun Fights! The Anthropocene!

Ruddiman et al think the anthropocene is a useful, necessary concept, but one which ought to remain someone nebulous, but the start ought to be 1945 (first atom bomb blast):

Defining the epoch we live in

Authors:

Ruddiman et al

Abstract:

Human alterations of Earth's environments are pervasive. Visible changes include the built environment, conversion of forests and grasslands to agriculture, algal blooms, smog, and the siltation of dams and estuaries. Less obvious transformations include increases in ozone, carbon dioxide (CO2), and methane (CH4) in the atmosphere, and ocean acidification. Motivated by the pervasiveness of these alterations, Crutzen and Stoermer argued in 2000 that we live in the “Anthropocene,” a time in which humans have replaced nature as the dominant environmental force on Earth (1). Many of these wide-ranging changes first emerged during the past 200 years and accelerated rapidly in the 20th century (2). Yet, a focus on the most recent changes risks overlooking pervasive human transformations of Earth's surface for thousands of years, with profound effects on the atmosphere, climate, and biodiversity.

OTOH, Lewis and crew think definitions are really important for science and if we're going to use the term 'anthropocene' we ought to it down to a formal start geologically & according to the GSSP standards:

Definitions are one of the bedrocks of science. However, W. F. Ruddiman et al. (“Defining the epoch we live in,” Perspectives, 3 April, p. 38) propose that the geological term Anthropocene should remain deliberately undefined and ambiguous. They recommend not formalizing the term because some inception dates miss important earlier human-induced environmental impacts, particularly widespread farming. We have sympathy for this view. However, defining the Anthropocene as a geological epoch must be based on evidence, including changes to the Earth system lasting millions of years and the existence of stratigraphic evidence marking such changes (1). All other geological time-units have agreed-upon dated markers or agreed-upon dates. The Anthropocene should not be treated differently.

link.

Certini et al agree with Lewis and crew about needing to make the anthropocene into something formal, but they suggest the anthropocene subsueme the holocene:

In their Perspective “Defining the epoch we live in” (3 April, p. 38), W. F. Ruddiman et al. write that in spite of its popularity, the Anthropocene still lacks an official onset. They propose that the term anthropocene be used informally (without the initial capital), which would avoid the constraints of a formal designation. We disagree.

[...]

Even if the impact of humans was not immediately major and uniform across the planet, what are a few thousand years of discrepancy between the end of the last glacial period and the dawn of the Anthropocene in comparison to the entire geological scale? Most transitions between the formally defined epochs would be much longer than the Holocene. Anthropocene seems a more reasonable name than Holocene for this combined time span, whose most characteristic trait is the human pressure on the planet. Holocene could possibly be the first stage of the Anthropocene, the one characterized by a soft and spotty human impact on Earth.

link.

Ruddiman counters the formalism is 'silly,' but does point out if the anthropocene is going to go formal, when to date it. The atom bomb or the start of the megafauna overkills?

Certini and scalenghe and Lewis and Maslin seem convinced that geoscience must rely heavily on formal stratigraphic nomenclature to move forward. This view likely originates from the centuries-long effort to compile the relative geologic age sequence, which was a monumental achievement, especially given religious and social opposition. The compilation required careful attention to stratigraphic principles such as superposition, index fossils, diachroneity, and facies changes. Over time, the findings became formalized in geologic nomenclature.

link.

Impacts of Human Colonization of Pleistocene Quaternary Sahul

The process, biotic impact, and global implications of the human colonization of Sahul about 47,000 years ago

Authors:

O’Connell et al

Abstract:

Comprehensive review of archaeological data shows that Sahul (Pleistocene Australia-New Guinea) was first occupied by humans ca. 47 ka (47,000 years ago); evidence for earlier arrival is weak. Colonizing populations remained low – perhaps two orders of magnitude below those estimated at European contact – for many millennia, and were long restricted to relatively favorable habitats. Though human arrival coincided with changes in native flora and fauna, these were mainly the products of climatic factors, not human interference. The genetic makeup of founding populations and their arrival date are consistent with the Late Dispersal Model of anatomically modern humans beyond SW Asia, beginning ca. 50 ka. Early Dispersal Models (120-70 ka) are not refuted, but draw no support from the Sahul record as currently understood.

15 Sites are Considered Undisputed Examples of Clovis Era Human Predation of Megafauna

Revisiting Paleoindian Exploitation of Extinct North American Mammals

Authors:

Grayson et al

Abstract:

In 2002, we assessed all sites known to us that had been suggested to provide evidence for the association of Clovis-era archaeological material with the remains of extinct Pleistocene mammals in North America. We concluded that, of the 76 sites we assessed, 14 provided compelling evidence for human involvement in the death and/or dismemberment of such mammals. Of these sites, 12 involved mammoth (Mammuthus), the remaining two mastodon (Mammut). Here, we update that assessment. We examine Clovis-era, and earlier, sites reported since 2002, as well as sites examined previously but for which additional information has become available. Our assessment leads us to exclude Hebior (Wisconsin) from the list of accepted sites, and to add El Fin del Mundo (Sonora) and Wally’s Beach (Alberta). There are now 15 sites on our list, providing what we find to be compelling evidence for human involvement in the death and/or dismemberment of five genera of now-extinct late Pleistocene mammals: Equus, Camelops, Cuvieronius, Mammut, and Mammuthus. As in 2002, however, we note this is a small fraction of the 37 genera that disappeared at the end of the Pleistocene, and for this and other reasons we remain highly skeptical that human overkill was responsible for their extinction.

Cause, Effect or Coincidence? Hydrological Cycle Changed at Pleistocene Quaternary Megafauna Extinction in Australia

Hydrological transformation coincided with megafaunal extinction in central Australia

Authors:

Cohen et al

Abstract:

Central to the debate over the extinction of many of Australia's last surviving megafauna is the question: Was climate changing significantly when humans arrived and megafauna went extinct? Here we present a new perspective on variations in climate and water resources over the last glacial cycle in arid Australia based on the study of the continent's largest lake basin and its tributaries. By dating paleoshorelines and river deposits in the Lake Eyre basin, we show that major hydrological change caused previously overflowing megalakes to enter a final and catastrophic drying phase at 48 ± 2 ka just as the giant bird, Genyornis newtoni, went extinct (50–45 ka). The disappearance of Genyornis and other megafauna has been previously attributed to "ecosystem collapse" coincident with the spread of fire-wielding humans. Our findings suggest a climate-driven hydrological transformation in the critical window of human arrival and megafaunal extinction, and the results call for a re-evaluation of a human-mediated cause for such extinctions in arid Australia.

The question becomes could people cause the hydrological change?  Fire was used extensively by the Aboriginals and that would have transformed things considerably.  Or did the climate change on its own and drive an extinction 30k years before the rest of the megafaunal extinctions?  Or was the arrival of humanity a coincidence?  or...?

During Pleistocene Megafauna Extinction, Coyotes Became More Gracile, Omnivorous

Ecological Changes in Coyotes (Canis latrans) in Response to the Ice Age Megafaunal Extinctions

Authors:

Meachen et al

Abstract:

Coyotes (Canis latrans) are an important species in human-inhabited areas. They control pests and are the apex predators in many ecosystems. Because of their importance it is imperative to understand how environmental change will affect this species. The end of the Pleistocene Ice Age brought with it many ecological changes for coyotes and here we statistically determine the changes that occurred in coyotes, when these changes occurred, and what the ecological consequences were of these changes. We examined the mandibles of three coyote populations: Pleistocene Rancho La Brean (13–29 Ka), earliest Holocene Rancho La Brean (8–10 Ka), and Recent from North America, using 2D geometric morphometrics to determine the morphological differences among them. Our results show that these three populations were morphologically distinct. The Pleistocene coyotes had an overall robust mandible with an increased shearing arcade and a decreased grinding arcade, adapted for carnivory and killing larger prey; whereas the modern populations show a gracile morphology with a tendency toward omnivory or grinding. The earliest Holocene populations are intermediate in morphology and smallest in size. These findings indicate that a niche shift occurred in coyotes at the Pleistocene/Holocene boundary – from a hunter of large prey to a small prey/more omnivorous animal. Species interactions between Canis were the most likely cause of this transition. This study shows that the Pleistocene extinction event affected species that did not go extinct as well as those that did.

Identifying the Source Quarry of the Clovis Points From the Gault Site

LA-ICP-MS analysis of Clovis period projectile points from the Gault Site

Author:

Speer

Abstract:

A key tenet of Clovis period hunter–gatherer mobility is the utilization of large ranges based on the appearance of exotic raw materials, particularly chert, in Clovis assemblages. The identification of the sources of chert in Clovis period assemblages is problematic as it has relied on macroscopic properties.

Macroscopic characteristics of chert can be highly variable in a single outcrop, occur across very large areas, and have correlates in unrelated and far removed contexts. An instrumental geochemical approach was utilized that potentially offers advances in the capacity to link chert artifacts to their sources. Trace element data was recovered from 33 Clovis period projectile points from the Gault Site (41BL323) using Laser Ablation-Inductively Coupled Plasma-Mass Spectrometry (LA-ICP-MS). This data was compared to trace element data recovered from 224 primary geologic samples of chert from multiple primary sources across the Edwards Plateau in Texas. The Clovis points were compared to the geologic sources using canonical discriminant analysis to establish group membership at three spatial scales: macro-regional (greater than 500 km), regional (between 30 and 500 km), and local (between 1 and 30 km). It was found at the macro-regional scale that 21 of the 33 Clovis points were to be geochemically similar to Edwards Plateau sources. At the regional scale, 15 of the 21 identified Edwards Plateau Clovis points could be attributed to a particular source. Lastly, only two Clovis points could be identified to particular sources at the local scale.

Youngest Gomphothere Site in Mexico (13.4kya) has Clovis Points (yup, they get et too)

An animal once believed to have disappeared from North America before humans ever arrived there might actually have roamed the continent longer than previously thought – and it was likely on the list of prey for some of continent's earliest humans, researchers from the University of Arizona and elsewhere have found.

Archaeologists have discovered artifacts of the prehistoric Clovis culture mingled with the bones of two gomphotheres – an ancient ancestor of the elephant – at an archaeological site in northwestern Mexico.

The discovery suggests that the Clovis – the earliest widespread group of hunter-gatherers to inhabit North America – likely hunted and ate gomphotheres. The members of the Clovis culture were already well-known as hunters of the gomphotheres' cousins, mammoths and mastodons.

Although humans were known to have hunted gomphotheres in Central America and South America, this is the first time a human-gomphothere connection has been made in North America, says archaeologist Vance Holliday, who co-authored a new paper on the findings, published this week in Proceedings of the National Academy of Sciences.

"This is the first archaeological gomphothere found in North America, and it's the only one known," said Holliday, a professor of anthropology and geology at the UA.

Holliday and colleagues from the U.S. and Mexico began excavating the skeletal remains of two juvenile gomphotheres in 2007 after ranchers alerted them that the bones had been found in northwestern Sonora, Mexico.

They didn't know at first what kind of animal they were dealing with.

"At first, just based on the size of the bone, we thought maybe it was a bison, because the extinct bison were a little bigger than our modern bison," Holliday said.

Then, in 2008, they discovered a jawbone with teeth, buried upside down in the dirt.

"We finally found the mandible, and that's what told the tale," Holliday said.

Gomphotheres were smaller than mammoths – about the same size as modern elephants. They once were widespread in North America, but until now they seemed to have disappeared from the continent's fossil record long before humans arrived in North America, which happened some 13,000 to 13,500 years ago, during the late Ice Age.

However, the bones that Holliday and his colleagues uncovered date back 13,400 years, making them the last known gomphotheres in North America.

The gomphothere remains weren't all Holliday and his colleagues unearthed at the site, which they dubbed El Fin del Mundo – Spanish for The End of the World – because of its remote location.

As their excavation of the bones progressed, they also uncovered numerous Clovis artifacts, including signature Clovis projectile points, or spear tips, as well as cutting tools and flint flakes from stone tool-making. The Clovis culture is so named for its distinctive stone tools, first discovered by archaeologists near Clovis, New Mexico, in the 1930s.

link.

And, yes, I guess it did hold up.

paper link when I see it.